With the developments of demands for compact and functional electronic products such as mobile phones or tablet PC with cameras, the requirements for the cameras driver become higher, especially for the optical image stabilization.
Thus optical image stabilizer (OIS) is applied to camera lens that requires high quality images, to prevent the image damage caused by the hand shaking during the use of the camera. Conventional OIS devices include VCM (voice coil motor) OIS devices, SMA OIS devices, VCM-SMA OIS devices, piezoelectric OIS devices, and stepper motor OIS devices, etc. The VCM-SMA OIS devices become popular due to the quick driving speed, small size, lower power and higher efficiency.
Following is the assembly process for this VCM-SMA OIS device.
First, assembling the VCM assembly in advance. Concretely, the conventional VCM assembly includes a yoke assembly and a lens holder assembly. The yoke assembly includes a yoke, a coil and four magnets located at four corners of the yoke, these elements are fixed temporarily by means of UV coating. And then, the yoke assembly is mounted to the lens holder assembly which includes a bottom, a lens holder, and four spacers. Concretely, the lens holder is supported by the bottom, and the four spacers are fixed temporarily on the bottom. During the assembly, the yoke assembly is covered on the lens holder assembly, and coating and soldering are proceeded to form the VCM assembly.
And then, the VCM assembly is mounted on a SMA unit to form the VCM-SMA OIS device.
However, the coating and soldering during the assembly process for the VCM assembly and the SMA unit are difficult, that is because coating and soldering positions will be covered by the yoke when the yoke assembly is covered on the lens holder assembly. Thus the element bonding for the VCM assembly must be made before it's mounted to the SMA unit, which causes the process complicated. During the assembly between the VCM assembly and the SMA unit, the coating and soldering space between the joining surfaces are very small due to the yoke cover, which makes the bonding further difficult. In addition, the coating and soldering must be performed artificially, and the efficiency and yield are low.
Thus, there is a need for improved assembly methods of a SMA assembly and an OIS device to overcome the drawbacks mentioned above.